Yes, the spike pokes out from the ball. 
This is a little tangential, but every kid has a spike these day, which means, unless they’re an Olympian, best selling author, or the child of the President, it’s the new round.
The best ECs are the ones kids would do no matter what, because they love doing them.
I agree with the definitions that others have written. “Well-rounded” used to be what AOs supposedly look for, but then well-rounded got to be regarded as boring and perhaps shallow. So the fad became to prize “spikiness” which is when a kid is passionate about a single subject, and proves it by having ECs (both organized and independent if possible) that demonstrate this passion. Some AOs have even been quoted as saying that they should be able to nickname your kid, like “The Orchid Kid” (for example if a kid maybe grows orchids as a hobby, and maybe also had a job at an orchid nursery, and then maybe also did a conservation project where they rescued and replanted rare native orchids found in roadside ditches.) AOs claim spikiness shows authenticity, but I think it is gamed, like everything else.
Heck, I went to college in the 70s and although we didn’t have this language, we all considered Harvard the place where kids who were really, really good at one thing went, and Yale was where the kid who was good at everything went.
Students have long fallen into these categories. and schools have long valued them…
They want a well-rounded kid with a spike or two. 
You mean like a spike protein?
Covid humor.
Yeah, I imagine college applicants as those desk stress balls with those little pokey things sticking out.
“Spike is the new round”…I will definitely remember that!
Why can’t kids just do the things they love, do the best they can in the highest level of classes they are able, have a life, and just apply and attend schools that they can get into?
Peer pressure, popular media, parents,…Although, I think that many are able to actually do “the things they love”…
Have you read the MIT “Applying Sideways” article? I am on an iPhone and don’t know how to link the article, but maybe somebody else can.
They can and most do. My son was accomplished at several things, but he did them, and still does, for his own joy.
Mine did this - no regrets. IME at the public school I work at most kids do this.
Some people take the ‘spiky’ thing too far. I remember a resume we were reviewing and everything this guy did had something to do with ducks. Ducks Unlimited, duck hunting, papers about ducks. His favorite game was probably Duck Duck Goose.
We made fun of him and he did not get the job.
Why can’t kids just do the things they love, do the best they can in the highest level of classes they are able, have a life, and just apply and attend schools that they can get into?
Mine did exactly that, took most rigorous classes available to her (because she wanted to, not because of college admissions, we didn’t know about that at the time) enjoyed her HS life, did activities she liked, had fun with her friends, and had a good college admissions run.
But:
Actually they are looking to build a well rounded CLASS
Okay. Let me try to revise my description of what colleges look for:
They want a well-rounded kid with a spike or two, the collection of which among the whole class is distributed evenly.
Except without the toxicity. 
Harvard and Yale were East Coast things that were utterly foreign to me and my friend group. I grew up in So Cal, equidistant to USC (both parents alumni) and the Claremont Colleges. I attended CC and graduated from a CSU, as did many/all of my friends. We just weren’t into that scene.
I applied to one college and there was zero stress. It was quite a shock back in 2014 when I began to understand that the expectations for applying to college in the Tri State area were totally different to what I knew in So Cal.
The term spike was certainly being used when I first came to CC. I think it’s silly, personally. I don’t think colleges give a hoot if someone is “spikey” or rounded. I think they simply care that kids are doing something outside of school that they care about and are interested in.
That’s all I want for my kids. I don’t care if they get into a T20, T30, T40 – doesn’t matter to me. But I do want them to do their best most of the time and get involved in things they love. Then they can apply to a smattering of the best colleges that meet their wants and needs, and make a choice they love. That’s what success looks like to me.
Back in the day when I applied in the early 80s, well rounded was the thing to be for the selective colleges vs. the students who only focused on grades, scores and academic ECs. Like holistic today, most of us thought it was just way for colleges to pick who they wanted, because even back then, there wasn’t room for every val or sal. Note, I was not academic so this is not sour grapes or anything :-).
